Adani has abandoned another deadline for securing finance on Australia's largest proposed coalmine, prompting Labor leader Bill Shorten to ridicule the idea that "some billionaire [will] come down in a helicopter and rescue" regional Queensland.

The Indian conglomerate had given itself until March 31 to secure investors for the $16 billion Carmichael coal project, but an Adani spokeswoman said this was "no longer the timeline".

It is the second time Adani has pushed back its deadline for financial close, after vowing last year to lock in investors by the end of December 2017.

The spokeswoman did not nominate a new deadline but said that Adani was still trying to sell a minority stake in the central Queensland project to help raise the $3.3 billion it needs to get it off the ground.

The Adani spokeswoman said the miner remained "100 per cent committed" to the project and "confident" of securing finance it had hoped would flow from a federal government loan, before that was torpedoed by the Palaszczuk government.

Mr Shorten told ABC Radio Brisbane that his position on the mine was "straightforward — this deal doesn't stack up by any measure that we've seen so far".

"They've missed more deadlines — I think in today's newspapers again, they're missing another deadline," he said, adding there were financial doubts and "environmental concerns".

Mr Shorten, after a series of public forums in Townsville, Mackay and Rockhampton this week, said there needed to be "a plan for jobs that just doesn't rely on a billionaire multinational coal company coming in with this very controversial project that has a lot of detractors".

"Labor's plan is to diversify the economy in central and north Queensland, not to pretend that there's going to be some billionaire come down in a helicopter and rescue it all, because I just don't believe that," he said.